People at a railway station in Seoul, South Korea watch a television showing President Donald Trump on Wednesday. Trump issued an apocalyptic warning to North Korea on Tuesday, saying it faces "fire and fury" over its missile program. (JUNG YEON-JE/AFP/Getty Images)

President Donald Trump issued an implicit warning to North Korea Wednesday morning, tweeting the U.S. nuclear arsenal is “far stronger and more powerful” than it ever has been.

A day after warning the United States would hit the North with “fire and fury” if Pyongyang repeated threats that it would strike American targets, Trump took to Twitter and appeared to signal he is prepared to use nuclear weapons against North Korea if conflict breaks out.

The president began the morning by retweeting several Fox News posts, including one declaring Guam-based U.S. Air Force jets are prepared to “fight tonight” should tensions with the North lead to war.

But then Trump weighed in with an implicit threat that only further escalates a fast-developing situation amid reports that the Kim Yong-un’s regime has developed a nuclear warhead that can ride atop its suddenly effective long-range missiles, which some analysts say could reach Chicago.

And the Obama administration years ago began a decades-long program to upgrade America's nuclear arsenal.

In a follow-on tweet, Trump was more measured, writing he hopes “we will never have to use this power,” but he also warned any would-be foes that “there will never be a time that we are not the most powerful nation in the world!”

As the president was tweeting about nuclear war, his secretary of state landed in Guam and told reporters he sees no imminent threat of war. The messages amounted to a good cop-bad cop routine, which previous U.S. presidents and cabinet officials have employed both domestically and while running foreign affairs.

“I think the president just wanted to be clear to the North Korean regime that the U.S. has the unquestionable ability to defend itself, will defend itself and its allies,” Tillerson said during a planned refueling stop on the island. “And I think it was important that he deliver that message to avoid any miscalculation on their part.”

The North Korean regime in recent days has threatened to strike Guam, which hosts U.S. military personnel and equipment.

“I never considered rerouting the trip back,” Tillerson said. “And I do not believe that there is any imminent threat, in my own view.”

“So the American people should sleep well at night,” he said.

Trump’s statement, if not a “red line,” is the closest he has come to drawing one one the world stage since taking office. He has harshly criticized former President Barack Obama for drawing on about Syrian President Bashar al-Assad, then opting against enforcing it.

The commander in chief also appears to be signaling just how he would respond to continued Kim regime threats against the United States, or a North Korean nuclear or conventional strike on American or allied targets in the region (Japan, South Korea). Trump and his team often dodge questions about how he might retaliate or conduct a U.S. military operation by saying he will never telegraph his plans or thinking.

Lawmakers from both parties on Tuesday immediately suggested Trump’s rhetoric went too far.

“I take exception to the president’s comments because you’ve gotta be sure you can do what you say you can do,” Senate Armed Services Chairman John McCain, R-Ariz., said on KTAR radio.

“I don’t think that some of the great leaders that I have admired would have taken that same path,” McCain said. “I don’t know how you deal with North Korea. That’s the problem with what he had to say. If we meet with fire and fury, they still can launch those rockets from across the [Demilitarized Zone] and strike Seoul, and I’m telling you that the catastrophe of that would be incalculable.”

And Senate Foreign Relations ranking member Ben Cardin, D-Md., said in a statement that Trump’s Tuesday remarks “were not helpful and once again show that he lacks the temperament and judgement to deal with the serious crisis the United States confronts.

“We should not be engaging in the same kind of blustery and provocative statements as North Korea about nuclear war,” Cardin said. “No one should think that a conflict with North Korea will be a quick little glorious war, or be tempted by false hopes that North Korea’s nuclear program can be destroyed with a single antiseptic surgical strike.”